This invention relates to metallurgical vessels and more particularly to a vessel adapted to be tilted and having a rotary joint for transporting process and cooling fluids from fixed sources to the vessel.
One type of metallurgical vessel for converting pig iron to steel, called a Q-BOP, includes one or more two-pipe tuyeres which extend through the refractory lining in the lower end of the vessel for delivering oxygen to molten metal contained therein. In order to prevent the rapid deterioration of the tuyere and the surrounding refractory, a hydrocarbon fluid such as propane, natural gas or light oil is injected through the gap between the inner and outer concentric tuyere pipes to provide a protective sheath in surrounding relation to the oxygen stream. In addition, such bottom tuyeres can be used for preheating the furnace charge which may contain solid material, such as scrap metal. When the tuyeres are used for normal oxygen blowing, the ratio of hydrocarbon to oxygen is relatively small and, accordingly, the gap between the inner and outer tuyere pipes is correspondingly small in relation to the area of the center pipe through which the oxygen is delivered. This limits the volume of fuel that can be delivered during preheating. As a result, a heavier hydrocarbon, such as oil, is used as a preheating fuel even though gas may normally be employed during the main oxygen blow. Because of different flow characteristics and the danger of accidental mixing, separate flow paths to the vessel are required for oxygen, oil, cooling water and hydrocarbon gas. It will also be appreciated that because the vessel pivots, it is necessary to deliver these fluids from fixed to rotary piping. Normally, cooling water and hydrocarbon fluids are delivered in separate flow paths through a first trunnion pin and oxygen is delivered through the other pin to prevent the accidental mixing of oxygen with any of the process fluids.
In addition to bottom tuyeres, Q-BOP vessels may also include concentric two-pipe top tuyeres both for preheating and for use during the metallurgical conversion process. As a result, an additional flow path is required through the first trunnion pin. One prior art system for delivering a plurality of fluids through one trunnion pin of a Q-BOP vessel is disclosed in U.S. Pat. No. 3,893,658. In this apparatus, concentric pipes extend through the trunnion pin for delivering cooling liquid and process fluids to the vessel. A rotary joint is coupled to the concentric pipes to permit the transfer of fluid from fixed sources to the pivoting vessel. Such prior art systems are not wholly satisfactory, however, because only a limited number of concentric pipes could be used in the limited space available in the trunnion pin.